# -*- test-case-name: twisted.web2.test.test_server -*-
# Copyright (c) 2001-2004 Twisted Matrix Laboratories.
# See LICENSE for details.


"""This is a web-sever which integrates with the twisted.internet
infrastructure.
"""

# System Imports
import cStringIO as StringIO

import cgi, time, urlparse
from urllib import quote, unquote
from urlparse import urlsplit

import weakref

from zope.interface import implements
# Twisted Imports
from twisted.internet import defer
from twisted.python import log, failure

# Sibling Imports
from pn.web import http, iweb, fileupload, responsecode
from pn.web import http_headers
from pn.web.filter.range import rangefilter
from pn.web import error

_version = 1.0

VERSION = "PNWS/%s" % _version
_errorMarker = object()


def defaultHeadersFilter(request, response):
	if not response.headers.hasHeader('server'):
		response.headers.setHeader('server', VERSION)
	if not response.headers.hasHeader('date'):
		response.headers.setHeader('date', time.time())
	return response
defaultHeadersFilter.handleErrors = True

def preconditionfilter(request, response):
	if request.method in ("GET", "HEAD"):
		http.checkPreconditions(request, response)
	return response

def doTrace(request):
	request = iweb.IRequest(request)
	txt = "%s %s HTTP/%d.%d\r\n" % (request.method, request.uri,
									request.clientproto[0], request.clientproto[1])

	l = []
	for name, valuelist in request.headers.getAllRawHeaders():
		for value in valuelist:
			l.append("%s: %s\r\n" % (name, value))
	txt += ''.join(l)

	return http.Response(
		responsecode.OK,
		{'content-type': http_headers.MimeType('message', 'http')},
		txt)

def parsePOSTData(request):
	if request.stream.length == 0:
		return defer.succeed(None)
	
	parser = None
	ctype = request.headers.getHeader('content-type')

	if ctype is None:
		return defer.succeed(None)

	def updateArgs(data):
		args = data
		request.args.update(args)

	def updateArgsAndFiles(data):
		args, files = data
		request.args.update(args)
		request.files.update(files)

	def error(f):
		f.trap(fileupload.MimeFormatError)
		raise http.HTTPError(responsecode.BAD_REQUEST)
	
	if ctype.mediaType == 'application' and ctype.mediaSubtype == 'x-www-form-urlencoded':
		d = fileupload.parse_urlencoded(request.stream)
		d.addCallbacks(updateArgs, error)
		return d
	elif ctype.mediaType == 'multipart' and ctype.mediaSubtype == 'form-data':
		boundary = ctype.params.get('boundary')
		if boundary is None:
			return failure.Failure(fileupload.MimeFormatError("Boundary not specified in Content-Type."))
		d = fileupload.parseMultipartFormData(request.stream, boundary)
		d.addCallbacks(updateArgsAndFiles, error)
		return d
	else:
		raise http.HTTPError(responsecode.BAD_REQUEST)

class StopTraversal(object):
	"""
	Indicates to Request._handleSegment that it should stop handling
	path segments.
	"""
	pass


class Request(http.Request):
	"""
	vars:
	site

	remoteAddr
	
	scheme
	host
	port
	path
	params
	querystring
	
	args
	files
	
	prepath
	postpath

	@ivar path: The path only (arguments not included).
	@ivar args: All of the arguments, including URL and POST arguments.
	@type args: A mapping of strings (the argument names) to lists of values.
				i.e., ?foo=bar&foo=baz&quux=spam results in
				{'foo': ['bar', 'baz'], 'quux': ['spam']}.

	"""
	implements(iweb.IRequest)
	
	site = None
	_initialprepath = None
	responseFilters = [rangefilter, preconditionfilter,
					   error.defaultErrorHandler, defaultHeadersFilter]
	
	def __init__(self, *args, **kw):
		if kw.has_key('site'):
			self.site = kw['site']
			del kw['site']
		if kw.has_key('prepathuri'):
			self._initialprepath = kw['prepathuri']
			del kw['prepathuri']

		# Copy response filters from the class
		self.responseFilters = self.responseFilters[:]
		self.files = {}
		self.resources = []
		http.Request.__init__(self, *args, **kw)

	def addResponseFilter(self, f, atEnd=False):
		if atEnd:
			self.responseFilters.append(f)
		else:
			self.responseFilters.insert(0, f)

	def unparseURL(self, scheme=None, host=None, port=None,
				   path=None, params=None, querystring=None, fragment=None):
		"""Turn the request path into a url string. For any pieces of
		the url that are not specified, use the value from the
		request. The arguments have the same meaning as the same named
		attributes of Request."""
		
		if scheme is None: scheme = self.scheme
		if host is None: host = self.host
		if port is None: port = self.port
		if path is None: path = self.path
		if params is None: params = self.params
		if querystring is None: query = self.querystring
		if fragment is None: fragment = ''
		
		if port == http.defaultPortForScheme.get(scheme, 0):
			hostport = host
		else:
			hostport = host + ':' + str(port)
		
		return urlparse.urlunparse((
			scheme, hostport, path,
			params, querystring, fragment))

	def _parseURL(self):
		if self.uri[0] == '/':
			# Can't use urlparse for request_uri because urlparse
			# wants to be given an absolute or relative URI, not just
			# an abs_path, and thus gets '//foo' wrong.
			self.scheme = self.host = self.path = self.params = self.querystring = ''
			if '?' in self.uri:
				self.path, self.querystring = self.uri.split('?', 1)
			else:
				self.path = self.uri
			if ';' in self.path:
				self.path, self.params = self.path.split(';', 1)
		else:
			# It is an absolute uri, use standard urlparse
			(self.scheme, self.host, self.path,
			 self.params, self.querystring, fragment) = urlparse.urlparse(self.uri)

		if self.querystring:
			self.args = cgi.parse_qs(self.querystring, True)
		else:
			self.args = {}
		
		path = map(unquote, self.path[1:].split('/'))
		if self._initialprepath:
			# We were given an initial prepath -- this is for supporting
			# CGI-ish applications where part of the path has already
			# been processed
			prepath = map(unquote, self._initialprepath[1:].split('/'))
			
			if path[:len(prepath)] == prepath:
				self.prepath = prepath
				self.postpath = path[len(prepath):]
			else:
				self.prepath = []
				self.postpath = path
		else:
			self.prepath = []
			self.postpath = path
		#print "_parseURL", self.uri, (self.uri, self.scheme, self.host, self.path, self.params, self.querystring)

	def _fixupURLParts(self):
		hostaddr, secure = self.chanRequest.getHostInfo()
		if not self.scheme:
			self.scheme = ('http', 'https')[secure]
			
		if self.host:
			self.host, self.port = http.splitHostPort(self.scheme, self.host)
		else:
			# If GET line wasn't an absolute URL
			host = self.headers.getHeader('host')
			if host:
				self.host, self.port = http.splitHostPort(self.scheme, host)
			else:
				# When no hostname specified anywhere, either raise an
				# error, or use the interface hostname, depending on
				# protocol version
				if self.clientproto >= (1, 1):
					raise http.HTTPError(responsecode.BAD_REQUEST)
				self.host = hostaddr.host
				self.port = hostaddr.port


	def process(self):
		"Process a request."
		try:
			self.checkExpect()
			resp = self.preprocessRequest()
			if resp is not None:
				self._cbFinishRender(resp).addErrback(self._processingFailed)
				return
			self._parseURL()
			self._fixupURLParts()
			self.remoteAddr = self.chanRequest.getRemoteHost()
		except:
			failedDeferred = self._processingFailed(failure.Failure())
			return
		
		d = defer.Deferred()
		d.addCallback(self._getChild, self.site.resource, self.postpath)
		d.addCallback(lambda res, req: res.renderHTTP(req), self)
		d.addCallback(self._cbFinishRender)
		d.addErrback(self._processingFailed)
		d.callback(None)

	def preprocessRequest(self):
		"""Do any request processing that doesn't follow the normal
		resource lookup procedure. "OPTIONS *" is handled here, for
		example. This would also be the place to do any CONNECT
		processing."""
		
		if self.method == "OPTIONS" and self.uri == "*":
			response = http.Response(responsecode.OK)
			response.headers.setHeader('allow', ('GET', 'HEAD', 'OPTIONS', 'TRACE'))
			return response
		# This is where CONNECT would go if we wanted it
		return None
	
	def _getChild(self, _, res, path, updatepaths=True):
		"""Call res.locateChild, and pass the result on to _handleSegment."""

		self.resources.append(res)

		if not path:
			return res

		result = res.locateChild(self, path)
		if isinstance(result, defer.Deferred):
			return result.addCallback(self._handleSegment, res, path, updatepaths)
		else:
			return self._handleSegment(result, res, path, updatepaths)

	def _handleSegment(self, result, res, path, updatepaths):
		"""Handle the result of a locateChild call done in _getChild."""

		newres, newpath = result
		# If the child resource is None then display a error page
		if newres is None:
			raise http.HTTPError(responsecode.NOT_FOUND)

		# If we got a deferred then we need to call back later, once the
		# child is actually available.
		if isinstance(newres, defer.Deferred):
			return newres.addCallback(
				lambda actualRes: self._handleSegment(
					(actualRes, newpath), res, path, updatepaths)
				)

		if path:
			url = quote("/" + "/".join(path))
		else:
			url = "/"

		if newpath is StopTraversal:
			# We need to rethink how to do this.
			#if newres is res:
				self._rememberResource(res, url)
				return res
			#else:
			#	 raise ValueError("locateChild must not return StopTraversal with a resource other than self.")

		newres = iweb.IResource(newres)
		if newres is res:
			assert not newpath is path, "URL traversal cycle detected when attempting to locateChild %r from resource %r." % (path, res)
			assert len(newpath) < len(path), "Infinite loop impending..."

		if updatepaths:
			# We found a Resource... update the request.prepath and postpath
			for x in xrange(len(path) - len(newpath)):
				self.prepath.append(self.postpath.pop(0))

		child = self._getChild(None, newres, newpath, updatepaths=updatepaths)
		self._rememberResource(child, url)

		return child

	_urlsByResource = weakref.WeakKeyDictionary()

	def _rememberResource(self, resource, url):
		"""
		Remember the URL of a visited resource.
		"""
		self._urlsByResource[resource] = url
		return resource

	def urlForResource(self, resource):
		"""
		Looks up the URL of the given resource if this resource was found while
		processing this request.  Specifically, this includes the requested
		resource, and resources looked up via L{locateResource}.

		Note that a resource may be found at multiple URIs; if the same resource
		is visited at more than one location while processing this request,
		this method will return one of those URLs, but which one is not defined,
		nor whether the same URL is returned in subsequent calls.

		@param resource: the resource to find a URI for.  This resource must
			have been obtained from the request (ie. via its C{uri} attribute, or
			through its C{locateResource} or C{locateChildResource} methods).
		@return: a valid URL for C{resource} in this request.
		@raise NoURLForResourceError: if C{resource} has no URL in this request
			(because it was not obtained from the request).
		"""
		resource = self._urlsByResource.get(resource, None)
		if resource is None:
			raise NoURLForResourceError(resource)
		return resource
		
	def locateResource(self, url):
		"""
		Looks up the resource with the given URL.
		@param uri: The URL of the desired resource.
		@return: a L{Deferred} resulting in the L{IResource} at the
			given URL or C{None} if no such resource can be located.
		@raise HTTPError: If C{url} is not a URL on the site that this
			request is being applied to.  The contained response will
			have a status code of L{responsecode.BAD_GATEWAY}.
		@raise HTTPError: If C{url} contains a query or fragment.
			The contained response will have a status code of
			L{responsecode.BAD_REQUEST}.
		"""
		if url is None: return None

		#
		# Parse the URL
		#
		(scheme, host, path, query, fragment) = urlsplit(url)
	
		if query or fragment:
			raise http.HTTPError(http.StatusResponse(
				responsecode.BAD_REQUEST,
				"URL may not contain a query or fragment: %s" % (url,)
			))

		# The caller shouldn't be asking a request on one server to lookup a
		# resource on some other server.
		if (scheme and scheme != self.scheme) or (host and host != self.headers.getHeader("host")):
			raise http.HTTPError(http.StatusResponse(
				responsecode.BAD_GATEWAY,
				"URL is not on this site (%s://%s/): %s" % (scheme, self.headers.getHeader("host"), url)
			))

		segments = path.split("/")
		assert segments[0] == "", "URL path didn't begin with '/': %s" % (path,)
		segments = map(unquote, segments[1:])

		def notFound(f):
			f.trap(http.HTTPError)
			if f.value.response.code != responsecode.NOT_FOUND:
				return f
			return None

		d = defer.maybeDeferred(self._getChild, None, self.site.resource, segments, updatepaths=False)
		d.addCallback(self._rememberResource, path)
		d.addErrback(notFound)
		return d

	def locateChildResource(self, parent, childName):
		"""
		Looks up the child resource with the given name given the parent
		resource.  This is similar to locateResource(), but doesn't have to
		start the lookup from the root resource, so it is potentially faster.
		@param parent: the parent of the resource being looked up.	This resource
			must have been obtained from the request (ie. via its C{uri} attribute,
			or through its C{locateResource} or C{locateChildResource} methods).
		@param childName: the name of the child of C{parent} to looked up.
			to C{parent}.
		@return: a L{Deferred} resulting in the L{IResource} at the
			given URL or C{None} if no such resource can be located.
		@raise NoURLForResourceError: if C{resource} was not obtained from the
			request.
		"""
		if parent is None or childName is None:
			return None

		assert "/" not in childName, "Child name may not contain '/': %s" % (childName,)

		parentURL = self.urlForResource(parent)
		if not parentURL.endswith("/"):
			parentURL += "/"
		url = parentURL + quote(childName)

		segment = childName

		def notFound(f):
			f.trap(http.HTTPError)
			if f.value.response.code != responsecode.NOT_FOUND:
				return f
			return None

		d = defer.maybeDeferred(self._getChild, None, parent, [segment], updatepaths=False)
		d.addCallback(self._rememberResource, url)
		d.addErrback(notFound)
		return d

	def _processingFailed(self, reason):
		if reason.check(http.HTTPError) is not None:
			# If the exception was an HTTPError, leave it alone
			d = defer.succeed(reason.value.response)
		else:
			# Otherwise, it was a random exception, so give a
			# ICanHandleException implementer a chance to render the page.
			def _processingFailed_inner(reason):
				handler = iweb.ICanHandleException(self, self)
				return handler.renderHTTP_exception(self, reason)
			d = defer.maybeDeferred(_processingFailed_inner, reason)
		
		d.addCallback(self._cbFinishRender)
		d.addErrback(self._processingReallyFailed, reason)
		return d
	
	def _processingReallyFailed(self, reason, origReason):
		log.msg("Exception rendering error page:", isErr=1)
		log.err(reason)
		log.msg("Original exception:", isErr=1)
		log.err(origReason)
		
		body = ("<html><head><title>Internal Server Error</title></head>"
				"<body><h1>Internal Server Error</h1>An error occurred rendering the requested page. Additionally, an error occured rendering the error page.</body></html>")
		
		response = http.Response(
			responsecode.INTERNAL_SERVER_ERROR,
			{'content-type': http_headers.MimeType('text', 'html')},
			body)
		self.writeResponse(response)

	def _cbFinishRender(self, result):
		def filterit(response, f):
			if (hasattr(f, 'handleErrors') or
				(response.code >= 200 and response.code < 300 and response.code != 204)):
				return f(self, response)
			else:
				return response

		response = iweb.IResponse(result, None)
		if response:
			d = defer.Deferred()
			for f in self.responseFilters:
				d.addCallback(filterit, f)
			d.addCallback(self.writeResponse)
			d.callback(response)
			return d

		resource = iweb.IResource(result, None)
		if resource:
			self.resources.append(resource)
			d = defer.maybeDeferred(resource.renderHTTP, self)
			d.addCallback(self._cbFinishRender)
			return d

		raise TypeError("html is not a resource or a response")

	def renderHTTP_exception(self, req, reason):
		log.msg("Exception rendering:", isErr=1)
		log.err(reason)
		
		body = ("<html><head><title>Internal Server Error</title></head>"
				"<body><h1>Internal Server Error</h1>An error occurred rendering the requested page. More information is available in the server log.</body></html>")
		
		return http.Response(
			responsecode.INTERNAL_SERVER_ERROR,
			{'content-type': http_headers.MimeType('text', 'html')},
			body)

class Site(object):
	def __init__(self, resource):
		"""Initialize.
		"""
		self.resource = iweb.IResource(resource)

	def __call__(self, *args, **kwargs):
		return Request(site=self, *args, **kwargs)


class NoURLForResourceError(RuntimeError):
	def __init__(self, resource):
		RuntimeError.__init__(self, "Resource %r has no URL in this request." % (resource,))
		self.resource = resource


__all__ = ['Request', 'Site', 'StopTraversal', 'VERSION', 'defaultHeadersFilter', 'doTrace', 'parsePOSTData', 'preconditionfilter', 'NoURLForResourceError']
